title: Conserved residues in RF-NH₂ receptor models identify predicted contact sites in ligand-receptor binding.
abstract: Peptides in the RF-NH2 family are grouped together based on an amidated dipeptide C terminus and signal through G-protein coupled receptors (GPCRs) to influence diverse physiological functions. By determining the mechanisms underlying RF-NH2 signaling targets can be identified to modulate physiological activity; yet, how RF-NH2 peptides interact with GPCRs is relatively unexplored. We predicted conserved residues played a role in Drosophila melanogaster RF-NH2 ligand-receptor interactions. In this study D. melanogaster rhodopsin-like family A peptide GPCRs alignments identified eight conserved residues unique to RF-NH2 receptors. Three of these residues were in extra-cellular loops of modeled RF-NH2 receptors and four in transmembrane helices oriented into a ligand binding pocket to allow contact with a peptide. The eighth residue was unavailable for interaction; yet its conservation suggested it played another role. A novel hydrophobic region representative of RF-NH2 receptors was also discovered. The presence of rhodopsin-like family A GPCR structural motifs including a toggle switch indicated RF-NH2s signal classically; however, some features of the DMS receptors were distinct from other RF-NH2 GPCRs. Additionally, differences in RF-NH2 receptor structures which bind the same peptide explained ligand specificity. Our novel results predicted conserved residues as RF-NH2 ligand-receptor contact sites and identified unique and classic structural features. These discoveries will aid antagonist design to modulate RF-NH2 signaling.
authors.affiliation: Biological Chemistry Department, University of Michigan, Ann Arbor, MI 48109-0600, USA.
authors.forename: C
authors.initials: C
authors.lastname: Bass
authors.affiliation: Biochemistry Undergraduate Program, University of Michigan, Ann Arbor, MI 48109-0600, USA.
authors.forename: C
authors.initials: C
authors.lastname: Katanski
authors.affiliation: Biochemistry Undergraduate Program, University of Michigan, Ann Arbor, MI 48109-0600, USA.
authors.forename: B
authors.initials: B
authors.lastname: Maynard
authors.affiliation: Biological Cellulare e Moleculare, Università di Cagliari-Monserrato, 09042 Monserrato, Cagliari, Italy.
authors.forename: I
authors.initials: I
authors.lastname: Zurro
authors.affiliation: Biological Cellulare e Moleculare, Università di Cagliari-Monserrato, 09042 Monserrato, Cagliari, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Mariane
authors.affiliation: Biological Cellulare e Moleculare, Università di Cagliari-Monserrato, 09042 Monserrato, Cagliari, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Matta
authors.affiliation: Biological Cellulare e Moleculare, Università di Cagliari-Monserrato, 09042 Monserrato, Cagliari, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Loi
authors.affiliation: Biological Cellulare e Moleculare, Università di Cagliari-Monserrato, 09042 Monserrato, Cagliari, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Melis
authors.affiliation: Biological Cellulare e Moleculare, Università di Cagliari-Monserrato, 09042 Monserrato, Cagliari, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Capponi
authors.affiliation: Dipartimento di Biologia Sperimentale, Sezione di Fisiologia Generale, Università di Cagliari-Monserrato, 09042 Monserrato, Cagliari, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Muroni
authors.affiliation: Dipartimento di Biologia Sperimentale, Sezione di Fisiologia Generale, Università di Cagliari-Monserrato, 09042 Monserrato, Cagliari, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Setzu
authors.affiliation: Biological Chemistry Department, University of Michigan, Ann Arbor, MI 48109-0600, USA; Biochemistry Undergraduate Program, University of Michigan, Ann Arbor, MI 48109-0600, USA; Visiting Professor Program, Università di Cagliari-Monserrato, 09042 Monserrato, Cagliari, Italy. Electronic address: nicholsr@umich.edu.
authors.forename: R
authors.initials: R
authors.lastname: Nichols
mesh_terms: D000818:Animals; D019835:FMRFamide / Q000737:chemistry / Q000378:metabolism; D007301:Insect Hormones / Q000737:chemistry / Q000378:metabolism; D008024:Ligands; D009479:Neuropeptides / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D017433:Protein Structure, Secondary; D043562:Receptors, G-Protein-Coupled / Q000737:chemistry / Q000378:metabolism*
chemical_list: D007301:Insect Hormones; D008024:Ligands; D009479:Neuropeptides; D043562:Receptors, G-Protein-Coupled; C076101:neuropeptide F; C077905:neomyosuppressin; D019835:FMRFamide
keywords: Dromyosuppressin (DMS); Drosulfakinin (DSK); FMRF-NH(2); FMRF-NH(2)-related peptide (FaRP); Neuropeptide F (NPF); Short NPF (sNPF)